Multiple discharge hydraulic pump



Jan. 11, 1966 R. w. BRUNDAGE 3,228,345

MULT IPLE D I S CHARGE HYDRAUL I C PUMP Original Filed March 11, 1960 2 Sheets-Sheet 1 INLET OUTLET OUTLET INVENTOR. ROBERT W. BRUNDAGE v ATTORNEY Jan. 11, 1966 R. w. BRUNDAGE 3,223,345

MULTIPLE DISCHARGE HYDRAULIC PUMP Original Filed March 11, 1960 2 Sheets-Sheet 2 m FIG. 2

WOW-2) OUT LET INVEN TOR. ROBERT W. BRUNDAGE War fiy/ ATTOR EY United States Patent 3,228,345 MULTELE DISCHARGE HYDRAULIC PUMP Robert W. Brnndage, 3i Bellerive Acres, Normandy 21, St. Louis, Mo.

(Briginal application Mar. 11, 1960;, Ser. No. 14,258, now Patent No. 3,123,707, dated Apr. 14, 1964. Divided and this application Mar. 9, 1964, Ser. No. 377,444

2 Claims. (Cl. 103126) This application is a division of my co-pending application Serial No. 14,258, filed March I l, 1960, now Patent No. 3,128,707, issued April 14, 1964.

This invention pertains to the art of hydraulic pumps of the positive displacement type and more particularly to an arrangement for hydraulically sealing a hydraulic pump capable of simultaneously delivering hydraulic fluid at two different output pressures and volumes.

The invention is particularly applicable to What is generally known as an internal gear type pump and will be described with particular reference thereto, although it will be appreciated that the invention may be equally applied to vane or rotating cylinder type hydraulic pumps or the like.

Furthermore, the present invention is particularly applicable to hydraulic pumps operable at what may be termed very high hydraulic pressures; that is to say, above 1,000 pounds per square inch and oftentimes approaching or exceeding 4,000 pounds per square inch. At such pressures, extremely high internal forces are developed and constructions and expedients usable at the lower pressures, are often unsatisfactory and inapplicable to the problems where the higher pressures are encountered.

Internal gear type hydraulic pumps are normally con prised of an internally toothed and an externally toothed gear member rotatable on spaced axes in a housing with the teeth of the gears in sliding sealing engagement. These teeth define axially open ended chambers which revolve and progressively increase in volume to a point of maximum volume which corresponds to the point of open mesh of the gears and then to a point of minimum volume which corresponds to the point of closed mesh of the gears. Each chamber has an opening leading therefrom which at open mesh is normally momentarily closed by a land and then moves into communication with a discharge port and continues in communication with such discharge port until it reaches closed mesh when it is again momentarily closed by a land and then moves into communication with an inlet port.

In internal gear type pumps, it has been conventional in the past to provide pressure sealing of the axial ends of the gears against the sealing face of the manifold member. This has been done by providing a sealing member in sealing engagement with the face of the gear members opposite from the manifold member, and exposing the axial end or portions of the end of this sealing member remote from the gears to the discharge pressure of the pump so that a force is created urging the sealing memher and manifold member into sealing engagement with the axial end of the gears proportional to the forces of the hydraulic pressures in the decreasing volume chambers tending to separate these members from the faces of the gears.

However, with a multiple pressure discharge pump, it has heretofore been dificult, if not impossible, to obtain the desired sealing force. If one pressure is employed for the purpose of providing the sealing force, and the other discharge pressure goes to Zero, then an excessive sealing force will result. On the other hand, if the sealing force is adjusted to provide for one of the discharge ports being at zero or intermediate pressure and this discharge port has an increase in pressure, then the sealing force is insufficient.

3,223,345 Patented Jan. 11, 1966 The present invention deals with this problem by automatically integrating the two discharge pressures to determine the necessary sealing pressure and deriving and maintaining such sealing pressure from one or the other of the discharge pressures whereby a sealing force is created which is always proportional to the two discharge pressures.

Thus, in accordance with invention, a piston has a plurality of discharge pressure surfaces of predetermined area facing in one direction and each exposed to one of the discharge pressures and a sealing pressure surface facing in the other direction and exposed to the sealing pressure, the piston being movable to close valve means communicating the higher of the two discharge pressures with the sealing pressure when the sealing pressure is of the desired magnitude.

The principal object of the invention is the provision of a new and improved pressure sealed hydraulic pump capable of supplying hydraulic fluid simultaneously at two different pressures wherein the sealing force is proportional to the two pressures.

Another object of the invention is the provision of a new and improved device for integrating the two pressure outputs on a hydraulic pump whereby sealing forces in the pump may be proportional to the two output pressures.

The invention may take physical form in certain parts and arrangements of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawing which is a part hereof and wherein:

FIGURE 1 is side cross sectional view of a hydraulic pump and a pressure integrator illustrating a preferred embodiment of the invention, the section of the pump being taken approximately on the line 1-1 of FIGURE 2; and,

FIGURE 2 is a cross sectional view of FIGURE 1 taken appproxirnately in the line 22 thereof and showing the interconnection of two of the discharge ports.

Referring now to the drawings wherein the showings are for the purposes of illustrating a preferred embodiment of the invention only, and not for the purposes of limiting same, the figures show a hydraulic pump comprised of a housing having an internal pumping cavity in which are mounted a plurality of pumping members defining a plurality of closed chambers which progressively in crease and decrease in volume as the members move relative to each other. While such members may take a number of different conventional forms, such as rotating cylinders with axially reciprocating pistons, or rotating vanes or the like, in the embodiment of the invention shown, and preferably, they comprise generally: an externally toothed gear member 11; and internally toothed gear member 12; a ported plate 6 engaging the right hand end of the gears 11, 12; a manifold member 14 engaging the left hand axial face of the ported plate 6; and, a sealing member 13 engaging the right hand axial end of the gears 11, 12.

Pumping members The gear member 11 and ported plate 6 are supported for rotation on the axis 15 of a shaft 16 and are keyed thereto by a key 17 fitting into keyways 18, 18 on the gear 11 and ported plate 6 respectively and keyway 19 on the shaft 16. The plate 6 is axially movable relative to the shaft 16. The internally-toothed gear member 12 is in turn supported for rotation about an axis 20 spaced from the axis 15 in a bearing member 17 which is loosely mounted and radially and axially movable in the housing cavity for reasons as are taught in my said co-pending application Serial No. 814,320, now Patent No. 3,034,447, issued May 15, 1962.

In this copending application, fluid film type lubrication was maintained between the outer surface of the ring gear 12 and the inner surface of the eccentric ring member 17 by biasing the eccentric ring member 17 axially into engagement with the sealing member 13 such that the bearing was axially closed at one end. The bias force was produced by means of the reaction force of the hydraulic fluid being discharged against one axial end of the eccentric member 17. In the embodiment of the invention shown, this reaction force is not available and in place a helical spring 1*5 is employed hearing at one end against the housing and at the other end against the left hand axial end of the eccentric ring members 17 The gear member 12 has one tooth more than that of the gear member 11 and these teeth are in sliding sealing engagement so that as the gear members 11, 12, they, along with the sealing and manifold members 13, 14, define a plurality of closed pumping chambers 21 which revolve on a closed path of movement and progressively increase in volume from a point A of minimum volume to a point B of maximum volume and then decrease in volume to the point of minimum volume A. The points A and B are in what may be termed the neutral plane through the two axes of rotation and it will be further noted that the gear teeth at the point A are in what may be termed closed mesh and at the point B at open mesh.

The ported plate 6 is in the form of a flat disc of a diameter at least greater than the diameter of the roots of the teeth of the gear 12 and has a plurality of axially extending passages 26 therethrough one for each chamber 21. In the preferred embodiment the inner gear member 11 has 6 teeth, and there are six passages 20, one located at the root of each tooth. Obviously, more or less teeth and passages may be provided. The right hand face of the plate 6 sealingly engages the left hand face of the gears 11, 12 and all fluid to and from the chambers 21 must pass through the passages 20.

It is to be noted that this ported plate may in some instances be dispensed with, but for use in connection with a pump having multiple discharge pressures, its use is advantageous for reasons which Will appear.

Housing The housing forms no part of the present invention, and as shown, includes a main part 22 generally in the shape of a cup, and a closure part 23 removably positioned in the open end of the cup 22 by any suitable means and sealed by means of an O-ring 26.

The main part 22 includes a base 27 having a circumferentially continuous surface 28 facing axially toward the open end of the cup. The main part 22 also includes a plurality of radially inwardly facing cylindrical surfaces 31, 32, 33 to the right of the surface 28 and which are progressively larger in diameter from left to right. In a like manner, the closure part 23 has cylindrical surfaces 34, 34' surrounding a housing opening through which shaft 16 passes.

Manifold member The shaft 16 extends into and is rotatably supported in the manifold member 14 which in turn is fixedly mounted in the housing in any suitable manner, but in the embodiment shown, has an axially facing surface 35' bearing against the surface 28 and a cylindrical surface 35 fitting within the cylindrical surface 32, such surfaces all being in sealing engagement. A radially extending lug 4 engaging in a corresponding groove of the housing locates the member circumferentially in the housing.

The housing base 27, in its upper half, has a generally semi-circular cavity 39 communicating with an inlet opening 36 and sealed from the remainder of the cavity of the main part 22 by means of this sealing engagement.

The manifold member 14 has on its right hand axial end, a surface 42 in sealing engagement with the left hand axial surface of the ported plate 6. An inlet manifold port 43 extending in an arcuate direction in the path of movement of the pumping chambers and of the passages 20 is formed in the sealing face 42 and extends axially through the manifold member 14 to communicate with the cavity 39. Additionally, first, second and third discharge manifold ports 44, 4t 45 are formed in the sealing surface 42 diametrically opposite from the inlet manifold port 43 which ports are in aligned relationships in an arcuate direction in the line of movement of the pumping chambers.

The circumferential ends of the various manifold ports are in circumferentially spaced relationship such that that portion of the sealing surface 42 between the arcuate ends of the ports forms the lands of the manifold member. Thus, between the ports 43, 4-4, there is a land 47 which may be termed the open mesh land. Between the opposite end of the port 43 and the adjacent end of the outlet port 45 is land 48 which may be termed the closed mesh land. Between ports 44, 41 is a first auxiliary land 49, while between ports 40 and 45 is a second auxiliary land 50, first and second and third being used herein to indicate the position of the auxiliary lands or ports as the case may be from the open mesh land in the direction of rotation.

The second discharge port 40 extends axially through the manifold member 14 and communicates with a discharge passage 51 formed in the base portion 27 of the housing. This passage 55 as shown in the drawing extends horizontally from the discharge port 40 and then turns at a right angle and extends downwardly to the exterior of the housing.

In like manner, the first and third discharge ports 44, 45 extend axially through the manifold member 14 and each communicate respectively with passages 52, 53 formed in the base 27 of the housing which passages 52, 53 are intercommunicated by means of a passage 58 extending through the housing and communicating with the exterior thereof.

Sealing member The sealing member 13 is mounted on the shaft 16 and desirably forms an integral part thereof. It may be Welded thereto, but in the preferred embodiment, has an interference fit with the shaft.

The sealing member 13 and shaft 16 are mounted for limited axial movement and for rotation within the housing by any suitable means such as a roller bearing 54 consisting of an outer race press-fitted into the housing and a plurality of circumferentially spaced cylindrical rollers engaging an outer cylindrical surface 56 on the sealing member 13.

The sealing member 13 has a surface 57 which extends radially outwardly beyond the outer surface of the ring gear 12 and is in sealing engagement with the right hand axial faces of the gears 11, 12 to close the right axial end of the chambers 21. The high pressure fluids in the high pressure chambers exert a radially ofiset axial force to the right on the member 13 which force as will appear, is opposed by hydraulic pressures in the pump cavity exerting an axial force on the surfaces 84, 86 of the sealing member 13 facing in an axial direction opposite to that of the surface 57. The size of the force is equal to the product of the hydraulic pressure and the sum of the area of the surfaces 84, 86 exposed to such pressures. Preferably the size of this force is approximately 14% greater than the size of the force in the opposite direction and as will appear, the pressures in the housing cavity are so proportioned in relation to the area of these two surfaces to produce the desired axial force. The area of the surface 84 exposed to such housing pressures is limited or held to zero (as is shown in the drawings) by a sealing ring 75.

Sealing ring The sealing ring 75 is generally in the shape of a sleeve and is axially slidable in a sealed relationship with the housing cavity defined by the cylindrical surface 34 by means of an O-ring 76 mounted on the outer surface of the ring. The ring surrounds the shaft 16 and has a left hand axiallyfacing surface 78 formed on a radially outwardly extending flange 78' in pressure sealing relationship with the right hand axially facing surface 84 of the sealing member 13. The ring 75 in conjunction with a packing member thus defines an internal cavity 79 which is at inlet pump pressure, it being noted that the cavity 79 is communicated with the inlet through the keyway 19, a small counterbore 91 in the surface 57, an opposite keyway 92 in the gear 11, and a groove or passage 93 in the manifold member 14.

A compression spring 81 between the base of the hous ing part 23 and the right end of the sealing ring 75 biases the surfaces 78, 84 into a limited pressure engagement. It is to be noted that this spring also presses the sealing member 13 into engagement with the axial faces of the gear 11, 12 and presses the gear 11, 12 into pressure engagement with the sealing surface of the manifold member 14. The spring 81 is relatively weak and simply provides an initial force to maintain the various surfaces in pressure engagement when the pump is not operating or when it is started into operation. The principal sealing force is the hydraulically produced force above-referred to.

The surface 78 engaging the surface 84 seals the pressures in the pump cavity 41 from the cavity 79 which is at low pressure. The sealing pressure between these surfaces is provided by the pressures in the cavity 41 exerting a force on a right hand axially facing surface 87 on the flange 7 8, the area of which surface is so proportioned that the force produced urging the surfaces together is just equal to the force of the pressures in the cavity 41 tending to separate these surfaces.

Pressure integrating As is known, the hydraulic pressures of the fluids in the high pressure chambers and in the discharge ports, create forces tending to separate the sealing member 13 from its sealing engagement with the gears 11, 21 and the sealing surface 5 of the ported plate 6 from the sealing surface 42 of the manifold member 14.

My co-pending applications Serial No. 656,657 now Patent No. 2,956,512, issued October 18, 1960, 656,117, now Patent No. 3,007,418, issued November 7, 1961, and 814,320, now Patent No. 3,034,048, dated May 15, 1962, together with my co-pending application Serial No. 16,765, now Patent No. 3,127,843, issued April 7, 1964, all describe an arrangement for creating an axial sealing force on the member to oppose the forces created by the hydraulic fluids in the chambers and discharge ports. In the apparatus described in all of these applications, the interior cavity of the pump has the discharge pressure communicated thereto, and this pressure bears on the side of the sealing member 13 axially remote from the gears and creates such a sealing force. Such an arrangement is satisfactory for a pump having a single discharge pressure. However, with a pump having multiple discharge pressures, this is not possible because if one of the discharge pressures is communicated to the housing cavity and the other discharge pressure goes to zero, then too high a sealing force results. On the other hand, if the discharge port which is communicated with the housing cavity drops or even goes to zero, then insufficient or no sealing force results.

In accordance with the present invention, both discharge pressures are combined to provide a pressure on the inside of the housing cavity and against the axial side of the sealing member 13 remote from the gears 11, 12 which is proportional to both of the discharge pressures.

While such means may take a number of different forms, in the embodiment of the invention shown in FIG- URE 1, a pressure integrator is provided. Such pressure integrator will preferably be formed as a component part of the pump housing or manifold plate. For the purpose of clarity, it is shown as separate, and in the embodiment shown, includes a housing M having an interior cylindrical bore with a piston P reciprocally mounted therein.

The housing M may take any desired form, but in the embodiment shown includes a main body portion and a closure member 151 threadably inserted therein and sealed by an O-ring 152.

The piston P includes a first portion 154 of a predetermined diameter and a second portion 155 of a predetermined and larger diameter. The portion 154 has a pressure surface 157 on its left hand axial end defining with the housing body 150 a pressure cavity 158 which is communicated with the second discharge port 40 through a conduit 159. This port may be considered as having a pressure P-1.

In a like manner, the left hand end of the larger piston portion 55 forms a pressure surface 165 defining with the bore and the outer surface of the piston portion 155 a pressure cavity 168 which communicates with the first and third discharge ports through a conduit 170. The ports may be considered as having a pressure P-2.

Also the larger piston portion 155 has a pressure surface 160 on its right hand axial end defining with the housing M a pressure cavity 162 which communicates through an internal passage 163 in the housing M and a conduit 164 with the interior of that portion of the pump cavity in communication with the right hand axial end of the sealing member 13. The cavity may be considered as having a pressure P-3.

It will be appreciated that the pressure in each cavity 158, 168 and 16.2 on its respective pressure surface, will exert an axial force on the piston P tending to move it axially either to the right or left depending upon the vector sum of the forces produced. This movement of the piston is employed to actuate a valve controlling flow of fiuid from either of the discharge ports to the housing cavity such that a hydraulic force of the desired amount is produced on the sealing member 13.

Such valve may take a number of different forms, but in accordance with the present invention, a preferred form of valve includes a valve member 172 in the form of a spherical ball axially movable in a valve chamber 173 formed on the interior of the piston portion 154. An axial passage 174 of a diameter smaller than that of the valve chamber 173 extends to the right therefrom and communicates with a radial passage 176 which in turn communicates with the cavity 168. The intersection of the walls of the passage 174 with the end wall of the valve chamber 173 forms a valve seat 178 against which the valve member 172 can move into sealing engagement.

A sleeve 180 threaded in the left end of the piston portion 154 has an axial passage 181 of a diameter smaller than the valve chamber 173 which communicates with the pressure cavity 158. The walls of the bore 181 where they intersect with the left end of the valve chamber 173 form a valve seat 182 which the valve member 172 can sealingly engage. Passages 183 in the piston and 184 in the housing, when aligned communicate the valve chamber with the passage 163 which, as previously pointed out, communicates with the interior of the pump cavity.

In operation, let it be assumed that the second discharge port is operating at a pressure P1 and the first and third discharge ports are operating at a pressure P-2 and that the interior of the cavity 41 is at a pressure P-3, such pressure P3 being selected in relation to the areas on the sealing member 13 above referred to provide the desired axial sealing force on the gears 11, 12. The forces tending to move the piston P to the right are equal to P1 times the area of the pressure surface 157 plus P-2 times the area of the surface while the forces tending to move the piston P to the left are equal to P-3 times the area of pressure surface 160. If it be assumed that the pressure P1 is zero, then hydraulic fiuid will flow from the conduit to the pressure cavity 168 to the passages 176, 174 to the valve chamber 173,

thence through the passages 183, 184 to the conduit 164 and pressure P-3 will rise. The valve member 172 is held against the valve seat 182 and the fluids will not flow to the conduit 159. Pressure P-3 therefore rises until the axial force of the pressures in the chamber 162 move the piston P to the left until the passage 183 moves out of communication with the passage 184 at which point further increase of pressure P-3 ceases.

If pressure P-3 drops due to leakage in the pump, the left hand axial force on the piston P also drops and the piston P moves to the right to bring two passages 183, 184 again into communication until the pressure P-3 again rises to the desired amount and the piston P again moves to the left so that the passages 183, 184 are no longer in communication.

Assuming that pressure P-1 rises, this means that the axial force to the right on the member 13 will also rise. A force is exerted to the right on the piston P and moves it to the right to bring the passages 183, 184 again into communication and fluid again flows from the conduit 170 until pressure P-3 again rises to Where the piston P can move to the left and cut off the flow of fluid from P2 to P-3. This action will continue as pressure P-1 increases until it equals pressure P-2.

If it now be assumed that pressure P-1 exceeds pressure P-2, the valve member 172 will move to the right and engage valve seat 178 to close pressure P-Z off from communication with the valve chamber 173. At the same time, however, pressure P-l is now communicated with the valve chamber 173 and can flow pressure P-3 and the action will continue as before.

By properly interrelating the various areas, a proper sealing force on the sealing member 13 can always be obtained .for any combination of output pressures.

It will thus be apparent that embodiments of the invention have been described in detail which accomplish all of the objectives heretofore set forth and others and provide a hydraulic pump of a multiple pressure discharge type which is improved in performance, a much more uniform flow of fluid to each discharge, and which always has a sealing force proportional to the two discharge pressures.

The invention has been described with reference to a preferred embodiment. Obviously modifications and alterations will occur to others upon a reading and understanding of this specification, and it is my intention to include all such modifications and alterations insofar as they come within the scope of the appended claims.

Having thus described my invention, I claim:

1. In a hydraulic pump of the pressure sealed type having a plurality of pump discharges at a plurality of hydraulic pressures including pumping members and a sealing member having a pressure surface adapted to be acted on by a hydraulic pressure and exert a sealing force on pumping members, the improvement which comprises a pressure integrator having first'and second pressure cavities each communicated with one of the pump discharge pressures, said integrator having a third pressure cavity communicated with the cavity defined by said sealing member pressure surface and means for selectively communicating the higher of the pressures in the first and second cavity to said third cavity and for cutting off such communication when the pressure in the third cavity reaches a predetermined relation to the pressures in the first and second cavities.

2. In a hydraulic pump arrangement wherein the pump has a pair of discharge ports operating at different discharge pressures, pumping chambers communicating with each of said ports and a pressure actuated sealing member for sealingly closing at least one end of the pumping chambers, the improvement which comprises: means for supplying a pressure to said sealing plate proportional to said two discharge pressures comprising in combination: a housing, a piston reciprocable in said housing having first and second pressure surfaces facing in one direction and a third pressure surface facing in the opposite direction, said surfaces defining with said housing first, second and third pressure cavities respectively, means communicating said first and second cavities one to each of said discharge ports, means communicating said third pressure cavity to a pump cavity at least in part defined by a surface on said sealing member, a valve chamber in said piston, passages communicating said first and second cavities with said valve chamber, means movable in said valve chamber to close communication of the one of said passages at the lower pressure with said chamber,

other passage means communicating said chamber with said third cavity, and valve means actuated by movement of said piston under forces on said third pressure surface for closing communication of said valve chamber with said third pressure cavity.

References Cited by the Examiner UNITED STATES PATENTS 2,312,686 3/ 1943 Campbell 1371 13 2,335,814 11/1943 Stevenson 137-111 2,420,622 5/1947 Roth et a1. 103l26 2,437,791 3/1948 Roth 103-126 2,487,732 11/1949 Schanzlin 103-126 2,811,979 11/1957 Presnell 137-112 2,853,023 9/1958 English 103-216 2,996,892 8/1961 Clark 1371l2 X 3,051,091 8/1962 Bennett et a1. 103216 DONLEY I. STOCKING, Primary Examiner.

WILLIAM F. ODEA, KARL I. ALBRECHT, Examiners. 

1. IN A HYDRAULIC PUMP OF THE PRESSURE SEALED TYPE HAVING A PLURALITY OF PUMP DISCHARGES AT A PLURALITY OF HYDRAULIC PRESSURES INCLUDING PUMPING MEMBERS AND A SEALING MEMBER HAVING A PRESSURE SURFACE ADAPTED TO BE ACTED ON BY A HYDRAULIC PRESSURE AND EXERT A SEALING FORCE ON PUMPING MEMBERS, THE IMPROVEMENT WHICH COMPRISES A PRESSURE INTEGRATOR HAVING FIRST AND SECON PRESURE CAVITIES EACH COMMUNICATED WITH ONE OF THE PUMP DISCHARGE PRESSURES, SAID INTEGRATOR HAVING A THIRD PRESSURE CAVITY COMMUNICATED WITH THE CAVITY DEFINED BY SAID SEALING MEMBER PRESSURE SURFACE AND MEANS FOR SELECTIVELY COMMUNICATING THE HIGHER OF THE PRESSURES IN THE FIRST AND SECOND CAVITY TO SAID THIRD CAVITY AND FOR 